Thursday, January 20, 2011

Rosco CalColor: The "Whatever You Want it to Be" Gels

At this point, most of us are probably pretty familiar with the gel fixes for fluorescent and tungsten ambient light situations. And for the trickier sources, you can check Rosco's free FIlter Facts booklet to learn what filter combinations can be used to balance lights such as sodium- or mercury vapor, etc.

But what about really weird, non-standard lighting environments, like a high school gym with sodium vapors and a brightly colored wall affecting the overall ambient color?

There's a gel kit for that, too. __________

CalColor = Chameleon

CalColor is a calibrated set of gels that can turn the light from your flash into any color you want. It is a stadardized set of color gels, in varying strengths, from all around the color wheel. By combining the gels you can dial in your flash just about anywhere.

This can be used to balance your flash for any color of ambient, too. First, you would do a custom white balance for your ambient. Then you add your (ungelled) flash to the scene.

Finally, you would build a "color pack" for your flash until you created the equivalent of white light in the new white balance. You can do it by eye, using your TFT screen as a guide. Essentially, you'll be building the complimentary color of the ambient light you have just balanced for.

Sadly, this could be an automated process if Nikon and Canon would merely share the information which is already inside your camera. But nope.

By stacking the gels (which come in several different densities in blue, cyan, green, yellow, red, magenta, pink, lavender) you can easily make any color. If you shoot in the same weird environment a lot -- such as that high school gym -- just make note of your color pack combo and it is an instant fix next time you shoot there.

The packs are about $50, but they are big enough (10x12") to easily create at least a dozen or so full sets when cut to speedlight size. In fact, I cut my pack big enough to cover a Profoto standard reflector and made several full speedlight sets with the scrap material.__________

20 Comments:

We just received in the Rosco CalColor Kit here at Midwest. We are running a special sale for strobist readers: $42.50! Call the store or online at www.mpex.com, Item code: VDP1047. Or click here: http://www.mpex.com/search.htm

Even if the camera displayed the custom WB number on the screen when you press play, you could take a WB shot and then go back and look and choose your gels from a cheat sheet..You can see the custom WB number when you edit in raw, so it would be just a matter of displaying that metadata on the screen. Is there no iPhone/android app for WB?

Sounds great, but I imagine you lose a lot of power if you combine more than two gels.

The problem I have with HS gyms isn't the weird color of their lights (although it generally sucks). The bigger problem--especially in older gyms--is that the lights continuously flicker in different color temperatures. You can't see it with the naked eye, but you sure notice it in the photos.

@ Joel- Yes and No, yes you could create a gel from printing off a solid color on transparency film, but Rosco has done an excellent job of creating calibrated colors and adding a layer of heat resistant coating.

Matthew is right. It's a bit of a pain to have to figure out and deal with the color, but it is much worse that the lights vary in both color and intensity. Same is true in the 'Friday Night Lights' of older football stadiums. Capture a great sequence and each frame might be a different color and intensity. Or worse, because the multiple light sources are not synchronized you might get a frame partially with one color cast and partially with another. Means you have to individually manipulate each image and that some otherwise great images with split color cast are nearly worthless.

It was noted, "I want a tool to check WB easily - I want to know which gel should be used."

You have one.

I always use my camera and the RGB histograms to pick my gels when matching artificial light. Also I generally do just fine with several different cuts each of CTO, Plus Green and Yellow. I have the CalColor gels et al, for correcting the flash to ambient but honestly CTO, Green and Yellow in different cuts cover 95% of the situations I encounter.

In a nutshell here is how I do it.

1. Use an Expodisk, coffee filter or even a white napkin or tissue over the lense (at full zoom) and set a custom white balance for the ambient light.

2. Now take a photo (autoexposure works fine for this) with the Expo/whatever still on the lense and confirm the white balance in the RGB histograms. The RGB peaks should each be at the same point on the horizonal scale. If they don't line up almost exactly, try again. Picture in review should look a neutral gray.

3. With the flash ungeled and off the camera, point it right at the lense (with expo/whatever) and snap another shot (ttl control for flash is fine, just be sure ambient isn't a factor). Look at the histograms. They will tell you how to gel the flash. If one color is low, add the similar color gel to bring it up. If one is high (typically blue) add the opposite color (yellow in the case of blue) and bring it down. This results in a lot less light loss than stacking lots of green and red/cto gels to bring down the blue.

4. Gel the flash and repeat step 3. After a bit of practice, one can look at the histograms and tell almost right away how much of each is needed to match the ambient. I generally get adequately close with just 1 or 2 attempts and darn near spot on with 2 or 3.

Essentially I don't care anymore what kind of lamps (assuming not a mix) are in the fixtures since I can match it in just a minute or two regardless of what it is.

Pretty easy and I am a bit surprised I never see photographers discussing or using this method on the various blogs. Have fun.

There is a reason why few cameras have great auto white balance on more than 2 different types of light sources. It is not easy (cheap) to implement a reliable color meter. Look at any review on dpreview for a camera and on the AWB section few, if any, will have a good results in both tungsten and fluorescent.

There are a couple color meters on the market that are light light meters but output a specific kelvin temp of the light hitting it but they are in the $500+ range (new).

Ideally, we'd see those sort of meters built into camera bodies and flash bodies which would make selecting gels a no-brainer. Until then trial and error is the way to match exiting lighting to a gel or combination of gels.

Thanks for the reference David. I shoot a lot of indoor sports that are lit with discharge lamps. I've tried using custom WB for non flash shots. I have also had to wing it using manual kelvin settings and determining what gels I had to use to make everything look right. Not every lighting situation is the same and I hope this provides a good road map for gelling in future shoots.

David Porter writes: "Sad but true, so many good ideas on how to make their products better and they don't seem to be listening too well."

Tell me about it! My best friend worked in the R&D division of one of them, was glad to listen to what photographers and videographers really need, gave plenty of brilliant ideas to management and was soundly ignored on all of them. She left in the end.